Faculty Opinions recommendation of A new role for RINT-1 in SNARE complex assembly at the trans-Golgi network in coordination with the COG complex.

Docking and fusion of transport vesicles/carriers with the target membrane involve a tethering factor–mediated initial contact followed by soluble N-ethylmaleimide–sensitive factor attachment protein receptor (SNARE)–catalyzed membrane fusion. The multisubunit tethering CATCHR family complexes (Dsl1, COG, exocyst, and GARP complexes) share very low sequence homology among subunits despite likely evolving from a common ancestor and participate in fundamentally different membrane trafficking pathways. Yeast Tip20, as a subunit of the Dsl1 complex, has been implicated in retrograde transport from the Golgi apparatus to the endoplasmic reticulum. Our previous study showed that RINT-1, the mammalian counterpart of yeast Tip20, mediates the association of ZW10 (mammalian Dsl1) with endoplasmic reticulum–localized SNARE proteins. In the present study, we show that RINT-1 is also required for endosome-to–trans-Golgi network trafficking. RINT-1 uncomplexed with ZW10 interacts with the COG complex, another member of the CATCHR family complex, and regulates SNARE complex assembly at the trans-Golgi network. This additional role for RINT-1 may in part reflect adaptation to the demand for more diverse transport routes from endosomes to the trans-Golgi network in mammals compared with those in a unicellular organism, yeast. The present findings highlight a new role of RINT-1 in coordination with the COG complex.

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Faculty Opinions recommendation of Dual roles of the mammalian GARP complex in tethering and SNARE complex assembly at the trans-golgi network.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.718529686.793498664 ◽

2014 ◽

Author(s):

Paul Gleeson

Keyword(s):

Snare Complex ◽

Dual Roles ◽

Complex Assembly ◽

Trans Golgi Network ◽

Golgi Network ◽

Garp Complex

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Syntaxin 16’s Newly Deciphered Roles in Autophagy

Cells ◽

10.3390/cells8121655 ◽

2019 ◽

Vol 8 (12) ◽

pp. 1655 ◽

Cited By ~ 3

Author(s):

Bor Luen Tang

Keyword(s):

Membrane Trafficking ◽

Functional Redundancy ◽

Transport Processes ◽

Snare Complex ◽

Dual Roles ◽

Trans Golgi Network ◽

Protein Receptor ◽

Sensitive Factor ◽

Golgi Network

Syntaxin 16, a Qa-SNARE (soluble N-ethylmaleimide-sensitive factor activating protein receptor), is involved in a number of membrane-trafficking activities, particularly transport processes at the trans-Golgi network (TGN). Recent works have now implicated syntaxin 16 in the autophagy process. In fact, syntaxin 16 appears to have dual roles, firstly in facilitating the transport of ATG9a-containing vesicles to growing autophagosomes, and secondly in autolysosome formation. The former involves a putative SNARE complex between syntaxin 16, VAMP7 and SNAP-47. The latter occurs via syntaxin 16’s recruitment by Atg8/LC3/GABARAP family proteins to autophagosomes and endo-lysosomes, where syntaxin 16 may act in a manner that bears functional redundancy with the canonical autophagosome Qa-SNARE syntaxin 17. Here, I discuss these recent findings and speculate on the mechanistic aspects of syntaxin 16’s newly found role in autophagy.

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The COG complex interacts directly with Syntaxin 6 and positively regulates endosome-to-TGN retrograde transport

The Journal of Cell Biology ◽

10.1083/jcb.201102045 ◽

2011 ◽

Vol 194 (3) ◽

pp. 459-472 ◽

Cited By ~ 63

Author(s):

Orly Laufman ◽

WanJin Hong ◽

Sima Lev

Keyword(s):

Steady State ◽

State Level ◽

Retrograde Transport ◽

Snare Complex ◽

Steady State Level ◽

Cog Complex ◽

Target Membrane ◽

Steady State Levels ◽

Retrograde Traffic ◽

Golgi Network

The conserved oligomeric Golgi (COG) complex has been implicated in the regulation of endosome to trans-Golgi network (TGN) retrograde trafficking in both yeast and mammals. However, the exact mechanisms by which it regulates this transport route remain largely unknown. In this paper, we show that COG interacts directly with the target membrane SNARE (t-SNARE) Syntaxin 6 via the Cog6 subunit. In Cog6-depleted cells, the steady-state level of Syntaxin 6 was markedly reduced, and concomitantly, endosome-to-TGN retrograde traffic was significantly attenuated. Cog6 knockdown also affected the steady-state levels and/or subcellular distributions of Syntaxin 16, Vti1a, and VAMP4 and impaired the assembly of the Syntaxin 6–Syntaxin16–Vti1a–VAMP4 SNARE complex. Remarkably, overexpression of VAMP4, but not of Syntaxin 6, bypassed the requirement for COG and restored endosome-to-TGN trafficking in Cog6-depleted cells. These results suggest that COG directly interacts with specific t-SNAREs and positively regulates SNARE complex assembly, thereby affecting their associated trafficking steps.

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Participation of the Syntaxin 5/Ykt6/GS28/GS15 SNARE Complex in Transport from the Early/Recycling Endosome to the Trans-Golgi Network

Molecular Biology of the Cell ◽

10.1091/mbc.e03-12-0876 ◽

2004 ◽

Vol 15 (9) ◽

pp. 4011-4022 ◽

Cited By ~ 110

Author(s):

Guihua Tai ◽

Lei Lu ◽

Tuan Lao Wang ◽

Bor Luen Tang ◽

Bruno Goud ◽

...

Keyword(s):

Snare Complex ◽

Recycling Endosome ◽

Trans Golgi Network ◽

B Subunit ◽

Protein Receptors ◽

Transport Assay ◽

Golgi Network ◽

Kinetics Of ◽

Kinetics Of Inhibition

An in vitro transport assay, established with a modified Shiga toxin B subunit (STxB) as a marker, has proved to be useful for the study of transport from the early/recycling endosome (EE/RE) to the trans-Golgi network (TGN). Here, we modified this assay to test antibodies to all known soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) that have been shown to localize in the Golgi and found that syntaxin 5, GS28, Ykt6, and GS15 antibodies specifically inhibited STxB transport. Because syntaxin 5, GS28, Ykt6, and GS15 exist as a unique SNARE complex, our observation indicates that these four SNAREs function as a complex in EE/RE-TGN transport. The importance of GS15 in EE/RE-TGN transport was further demonstrated by a block in recombinant STxB transport in HeLa cells when GS15 expression was knocked down by its small interfering iRNA. Morphological analyses showed that some GS15 and Ykt6 were redistributed from the Golgi to the endosomes when the recycling endosome was perturbed by SNX3-overexpression, suggesting that GS15 and Ykt6 might cycle between the endosomes and the Golgi apparatus. Further studies indicated that syntaxin 5 and syntaxin 16 exerted their role in EE/RE-TGN transport in an additive manner. The kinetics of inhibition exhibited by syntaxin 16 and syntaxin 5 antibodies is similar.

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The Arf GAP SMAP2 is necessary for organized vesicle budding from the trans-Golgi network and subsequent acrosome formation in spermiogenesis

Molecular Biology of the Cell ◽

10.1091/mbc.e13-05-0234 ◽

2013 ◽

Vol 24 (17) ◽

pp. 2633-2644 ◽

Cited By ~ 25

Author(s):

Tomo Funaki ◽

Shunsuke Kon ◽

Kenji Tanabe ◽

Waka Natsume ◽

Sayaka Sato ◽

...

Keyword(s):

Membrane Vesicles ◽

Round Spermatid ◽

Snare Complex ◽

Coated Vesicle ◽

Vesicle Budding ◽

Trans Golgi Network ◽

Protein Receptor ◽

Acrosome Formation ◽

Golgi Network ◽

Coated Membrane

The trans-Golgi network (TGN) functions as a hub organelle in the exocytosis of clathrin-coated membrane vesicles, and SMAP2 is an Arf GTPase-activating protein that binds to both clathrin and the clathrin assembly protein (CALM). In the present study, SMAP2 is detected on the TGN in the pachytene spermatocyte to the round spermatid stages of spermatogenesis. Gene targeting reveals that SMAP2-deficient male mice are healthy and survive to adulthood but are infertile and exhibit globozoospermia. In SMAP2-deficient spermatids, the diameter of proacrosomal vesicles budding from TGN increases, TGN structures are distorted, acrosome formation is severely impaired, and reorganization of the nucleus does not proceed properly. CALM functions to regulate vesicle sizes, and this study shows that CALM is not recruited to the TGN in the absence of SMAP2. Furthermore, syntaxin2, a component of the soluble N-ethylmaleimide–sensitive factor attachment protein receptor (SNARE) complex, is not properly concentrated at the site of acrosome formation. Thus this study reveals a link between SMAP2 and CALM/syntaxin2 in clathrin-coated vesicle formation from the TGN and subsequent acrosome formation. SMAP2-deficient mice provide a model for globozoospermia in humans.

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The Tlg SNARE complex is required for TGN homotypic fusion

The Journal of Cell Biology ◽

10.1083/jcb.200104093 ◽

2001 ◽

Vol 155 (6) ◽

pp. 969-978 ◽

Cited By ~ 29

Author(s):

Jason H. Brickner ◽

Jennifer M. Blanchette ◽

György Sipos ◽

Robert S. Fuller

Keyword(s):

Membrane Fusion ◽

Fusion Reaction ◽

Snare Complex ◽

Snare Proteins ◽

Attachment Protein ◽

Trans Golgi Network ◽

Rab Protein ◽

Protein Receptor ◽

Golgi Network ◽

Antibody Inhibition

Using a new assay for membrane fusion between late Golgi/endosomal compartments, we have reconstituted a rapid, robust homotypic fusion reaction between membranes containing Kex2p and Ste13p, two enzymes resident in the yeast trans-Golgi network (TGN). Fusion was temperature, ATP, and cytosol dependent. It was inhibited by dilution, Ca+2 chelation, N-ethylmaleimide, and detergent. Coimmunoisolation confirmed that the reaction resulted in cointegration of the two enzymes into the same bilayer. Antibody inhibition experiments coupled with antigen competition indicated a requirement for soluble NSF attachment protein receptor (SNARE) proteins Tlg1p, Tlg2p, and Vti1p in this reaction. Membrane fusion also required the rab protein Vps21p. Vps21p was sufficient if present on either the Kex2p or Ste13p membranes alone, indicative of an inherent symmetry in the reaction. These results identify roles for a Tlg SNARE complex composed of Tlg1p, Tlg2p, Vti1p, and the rab Vps21p in this previously uncharacterized homotypic TGN fusion reaction.

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